Stoker control



Oct. 31, 1939. HELLMANN ET AL 2.178.171

I STOKER CONTROL Filed 001:. 27, 1957 3 Sheets-Sheet l Oct 1939. F. A.HELLMANN El AL 2.178.171

STOKER CONTROL Filed Oct. 27, 1937 s Sheets-Sheet 2 MIM flatly R5721160.???

may x W W 3 1939. F. A. HELLMANN ET AL 2,178,171

STOKER CONTROL Filed Oct. 27, 1937 3 Sheets-Sheet 3 mwwm wound/3Patented Oct. 31, 1939 UNITED STATES:

PATENT OFFICE Frederick A. Hellmann,

Chattanooga, Tenn., and

Harry R. Statham, F 8118 Church, Va.

Application October 27, 1937, Serial No. 171,376

15 Claims.

a furnace or boiler so that the amount of coal and amount of air fed tothe furnace are synchronized with each other and in accordance with theamount of unburned coal in the combustion chamber of the furnace, tothus provide a balanced ration of coal and air.

Another object of the invention is, to provide a control for a coalstoker where installed in a boiler or furnace, or as an attachmentthereto,

whereby the stoker is operated entirely automatically andin conjunctionwith ,the usual ther-.

inostatic or other controls of the stoker.

Another object of the invention is to correct fire depth so that theproper amount of air and coal will be fed into the combustion chamberand at all times.

Still another object of the invention is the provision of an automaticdamper control installed on the intake of the fan.

A further object of the invention is the provision of an automaticdamper the operation of which is controlled by the condition in the firebox of the furnace.

Other objects will appear hereinaiter throughout the specification. r

In the drawingse Figure 1 is a side elevation of a furnace, a Stokerhaving the improved control attached thereto, the furnace being shown insection, and

the coal and air conduits inpartial section;

Figure 2 is a front elevation of the adapter plate and damper operatingassembly, certain I parts being shown in section; Figure 3 is a topplan. view of the shown in Figure 2; I

Figure 4 is aside elevation of the structure shown in Figure 2,, sviewed from the left of said figure; I

Figure 5 is a side elevation of the structure shown in, Figure 2, asviewed from the right of said figure;

Figure 6 is a front elevation of a modified form of a damper controlswitch;

V c Figure 7 is a side elevation 'of the structure shown in Figure 6 asviewedfrom the right hand side, and

structure Figure 8 is a wiring diagram ofthe electric controls of themotors for operating the coal feeding mechanism and air. blowermechanism.

In the drawings, the numeral l designates'a furnace, although any othersuitable heating apparatus may be used, and 2 indicates a stoker of anyconventional type. It is common practice to provide such stokers with acoal feeding i conduit '3 having the usual. feed screw, not shown,located therein and an air conduit 4 located therebelow, said conduitsbeing separated by a horizontal partition 3', as shown in Fig ure 1. Thenumeral 5 indicates a coal hopper, 0 the lower portion of which isprovided with an aperture leading into the conduit 3.

The fan blower is indicated by the numeral 6. Such fan blowers areusually provided with a manually controlled damper, to control the en-15 trance of air into the blower. The outlet i connects with a pipe 8,the opposite end of which opens into the air conduit 4. r

In the illustrative example of one application of this invention, asshown in the drawings, the 20 "usual side plate which supports amanually operated damper of the fan-blower, is removed, and there isattached in place thereof, an adapter plate 9, which is bolted to thecasing by the conventional bolts [0. provided with an aperture ll,forming an air intake to the eye of the blower. Mounted on the plate inalignment with the aperture] II, is a thimble l2, forming an air inletconduit, the diameter of which is substantially the same 30 diameter asthe aperture II.

Mounted on shafts l3 and I4, is a damper ll. Said shafts extend throughapertures or bearings inthe thimble l2.

Rigidly mounted on the adapter plate is a 35 float chamber l6 and anhermetically sealed chamber i1; said chambers are connected to eachother by means of a pipe I8 which passes through-the lower extremitiesof the chambers. The chambers are partially filled, preferably with 40 anon-vaporizing liquid i9, such as oil, or a non-inflammable liquid maybe used instead of oil. Within the chamber i6 is' a float 20, having a astem 2| and a right-angled portion 22, which latterPIOjEOtSEfill'Ollghan aperture 23 o! a t crank 24. is rigidly attachedto the shaft l3 so that asthe floatrises and falls, the damper i5 isturned from the fully closed posi-. tibn' shown in Figures 1 and 2, andin dotted lines in Figure 4, to the inclined position indicated indotted lines in Figure 3, or to the fully, 'open' or horizontal positionshown in. dotted lines in Figure 4.

An air pressure pipe 25 extends into the hermetically sealed chamber I!so that its open end The adapter plate is 25' 26 is at all times in.communication with the air space above the liquid l9. The opposite, end

of the pipe 25 communicates with the interior oi. the pipe 8, but thisend may be connected to the air conduit 4, instead of the pipe 8, asshown. In either instance, the air space above the liquid in thehermetically sealed chamber I1 is exposed to pressure conditions withinthe pipe 8, and conduit 4. Such. pressure conditions are affected by therate burning, and the amount of coal within the furnace I. The coal feedconduit 3 and air conduit 4 are connected, as is the usual practice, soas to feed coal and air to the retort ;21, which retort is provided withthe usual tuyeres, not shown.

Referring now particularly to Figure 5, there is rigidly mounted on theshaft |4, so as to be rotated thereby, when the damper |5 is rotated, adisk 28. Foxed on the disk are spring clips 38 and held by these clipsis a single pole, double throw, mercury tube switch 3|, controlling theoperation of the two-speed motor 32, which drives the fan blower 6. Thenumeral 33 indicates a pivot having an arm 34 adapted to pivotthereabout. spring clips 35, which rigidly hold the single throw mercuryswitch 36, which latter controls the coal feed screw driving motor 31.The opposite end of the arm 34 may be adjustably positioned and held bythe rack 38, mounted on the disk 28. By this means the proper adjustmentmay be effected for causing the coal feed motor 31 to operate underdifferent conditions of use, and in accordance with the size of thefurnace I, the grade of coal being used, furnace draft conditions, etc.

Referring to Figure 8, the numerals 39 and 40 are line connections froma source of current. The wire 38 is connected to the left end of themercury tube switch 3| by means of a wire 4|, and to the right end ofswitch 36 by wire 42. The wire 44 connects the left end of switch 3| toa terminal 45 of the two-speed fan motor. Wire 46 connects the right endof switch 3| to terminal 41 of this motor. Wire 48 connects the rightend of mercury tube switch 36 to terminal 43 of the coal feed motor.Line connection 40 is connected to terminal 50 of said motor by wire 5|,and is connected to terminal 52 of the fan motor by wire 53. r

In place of the single pole, double throw, mercury switch 3|, shown inFigures 1 to 5, the speedof the fan motor 32 (which motor would be ofthe single speed variety), may be controlled by a rheostat, such as therheostat shown in Figures 6 and '1, wherein is shown the disk 28'rigidly mounted on the shaft l4, and turnable therewith. The shaft I4 isrotated by damper I! by means of the shaft l3, in the same manner asdescribed in connection with the form shownin Figures 1 to 5.

Mounted on the thimble I2 is an insulated support 54 having a pluralityof. contacts 55', having-the usual resistances and to which areconnected wires 58'. The terminal 51' is mounted so as to extend throughdisk 28'. Attached to the terminal 51 on opposite side of the disk is a.wiping contact 58'. As the'damper l5 is rotated, due to differentconditions of pressure in conduit 8, the disk 28! is rotated and as thistakes place, the wiping contact 58' moves into successive engagementwith the several contacts 55', thus changing the speed of the fan motorand increasing or decreasing the amount of air forwd into conduit 4 andretort 21. All of the The arm 34 has attached thereto wires 56 connectto one terminal, and wire 53' connects to the other terminal of a fanmotor which, in the present instance, is of the ordinary type. Thebundle of wires leading to the several contacts is indicated by thenumeral 68'.

Operation Assuming that the stoker has been shut down, with the damperin a closed or substantially closed position; in this position the diskis, as shown in Figures 1, 2 and 8, with the mercury in tube 3| at theright end of the tube so as to allow current to pass from Wire 42 towire 46, and thence to the lower speed terminal 41 of the fan motor. Aswill be seen by referring to Figure 5, the terminals within the tube 36,which are connected to wires 43 and 48, are connected by the mercurywithin the tube so that the coal feed motor is thereby operated. In thisposition, the fan motor is operated at low speed, and the coal feedmotor is running, to thereby feed coal into the retort. As the internalair pressure within the conduit 4 is built up, due to the increasingdepth of the fire bed as the coal is fed to the same, and the consequentinability of the air to escape only slowly through the retort, airpressure increases in conduit 4 and pipe 8, as well as in the air spacewithin the chamber ll, because of the connecting pipe 25. Increased airpressure in chamber |1 forces the fluid l9 through pipe |8 into floatchamber l6, thereby raising the float 20 which, by means of the crank24, rotates shafts l3 and I4 and the damper I5.

It is to be understood that with the damper closed, and the fan rotatingat slow speed, some air is being forced continuously into conduit 4 andretort 21, due to the fact that some air enters around the periphery ofthe damper |5.

The opening of the damper l5 permits the entrance of additional air tobe sucked into the fan chamber, whereupon such additional air is forcedthrough pipe 8 and conduit 4, and into the retort 21, where it passesthrough the tuyre gates.

' As the damper |5 continues to open, the disk 28 rotates in acounterclockwise direction (see Figure 5). Such rotation of the disk 28continues until the mercury within the tube 3| moves from the right endof said tube to the opposite or left end thereof, thereby completingcontact between the terminals of tube 3| which are connected to the twowires 4| and 44, to thereby switch the fan motor from low to high speed.

Simultaneously, the rotation of the disk 28 will cause the tube 38 tomove to a position (according to its position of adjustment) where itsleft end becomes lower than its right end, whereupon the mercury leavesthe right end of the tube, thereby breaking the connection between thewires 43 and 48, and stopping the coal feed motor. In this position ofthe disk, the coal feed motor has stopped, but the fan motor continuesto operate at high speed. This operation continues until such time asthe fuel bed is burned down to a point which allows air to pass morefreely through the fire bed, whereupon the pressure gradually drops inconduit 4 and pipe I. The drop in pressure allows the damper to moveback, or in a reverse direction, toward the closed position, the diskmoving in a clockwise direction. As the disk moves in a clockwisedirection, the lower tube rotates to such position that its right endbecomes lower than the left end, whereupon the mercury within tube 36moves back so as to again connect the wires 43 and 48, and thereby tionof said motor in accordance with the amount starting the coal feed motoroperating again, and the tube 3| again assumes the position shown inFigure 5 to thereby again switch the fan motor to its low speed ofrotation.

By the abovedescribed operation, it will be un derstoodthat both thefeeding of air and .coal is controlled by the depth of the fuel bed andthe control of each is synchronized with the other,

thus insuring a balanced ration of feed for the furnace. v

The control shown in Figures 6 and 7 operate coal and air substantiallythe same as that shown in other figures, except that the'fan motor isgradually accelerated, or decelerated, according to the direction-inwhich the disk 28" is moved. In the position-shown in Figure-f7, themotor isrunningj at low speed. Itsspeedis acbelerated asthel diskrotates in a counterclockwise' direction,;and as pressure is being-buiIt -upflinF-Qtheconduit-J until it reaches its speed, gabout -the';time when the damper reaches its openpo'sitmn-r'J cintoacombustion-chamber including a damper,

Also, the coal motor, according to the position of.

adjustment to which the coal motor thermostat-.

' switch 36' has been set, will be cut outof circuit during the rotationof disk 28. Subsequently, as. r the coal in the combustion chamber burnsshown, a condition of gradually reduced pressure in conduit results, andthe parts slowly return to the position shown in Figures ,6 and 7, withthe coal motor again operating and theian motor running at reducedspeed, with thedamper IS in" closed or substantially closed position.The parts remain in this position until there is again in, conduit Lacondition of higher pressure whereupon the operation is repeated.

The invention is not limited to the construction shown and described,such being merely one application of the invention. ,We desire to belimited only to the extent indicated by the appended claims. We'claim: 1

1. In a coal stoker of the character wherein the stoker is provided withmeans for feeding coal and air into acombustion chamber includ- 7- ing adamper, acoal passageway and an air j ipassageway; the combination withsuch. means,'

of damper"control meansfoperatively connected to said air passasewam andelectrically operated switch means adapted to be actuated by said dampercontrolmeans for-controlling the operationlofisaid coal feeding and airfeeding means; yand said damper by means of said damper control meansaccording to theamount of unburned iuel within .conibustior'rchainber,-said first named means additionally'f ncludins a motor for feeding f00111 n fa sepaifittegmotor for feeding gain said last;named-'mot'orhavingimeansffor yaryingthe amou t or airfed tu sle, (combustion"chamber synchmmm hhel movements 1 m mpen I V,

. 2. an a-coalstoker, oI -tlicfoh 7$ it wh r i oi the 'stoker isprovided "with means" {for leading-9f 1 coal and air into acombustionchamber; the come;

theiliquid in saidlast-vnamed chamber, and its bination with such means,of automaticmeans operativelyconnected to'saidi'firstenamed means c M sand-switch means electrically connected to both for controlling theoperationroi' said coalv feeding may regulate said damper and control'the opera r and air into a combustion chamber; means operativelyconnected to said first-named means for controlling the amount ofairaccording to the amount of unburned fuel within said combustionchamber, said control means including a damper and electrical switchmeans operated thereby, .and electrical connections from said switchmeans to said means first named, said 'first named means additionallyincluding a motor for feeding coal'and'a separate motor for feeding saidlast namedmotor having means for Lvaryirig the amount of air-fed to saidcombustion. v

chamber insynchronismwith the movements of Zamfla ne .-L i. k 4. QZrassoQatiDn with a coal feeding stoker, which comprises for feeding coaland air an .electricmotorllor pperating said air feeding means-and asecond"riibtnr ifor'operating said coal feeding means; mean pperanveiyconnected to saidjmotors and aamperaanag ngseparate electric switchesfor said motors-am ectrical connections thereto, and a niechani ectionto said damper for controlling the amoimtfotgiair and coal according-totheamount-golunbiarnbdal fuel within sai combustionchamber. I:

5; In a coalstokerof the character other? the stokeris provided withmotor means iorfeed,

.ing coal and air-into a combustion chamber and including a blowerdriven by said motor means, a damper for said blower, and air and-coalpassageways to said combustion chamber; the; combination with suchmeans, of i switch means actuated by said damper and electrlcallyconnected to said motor means, and pressure means connected. tosaiddamper for operating said damper, said pressure means being actuated bydifi'erences ofpressure 1 within said air passageway, said motor meansincluding [a multi-speed motor {foi' driving said blower to varytheamount of air fed to said combustion chamber in syn-' chronism with themovements of said damper. I

'6. In a coal stoker ofv the character wherein the stoker is providedwith coal feed means, a

motor for driving'said coal feed means, an air blower, a second motorfor operating said air blower, :a hopper for coal, a retort, a coalpassageway from said hopper to said retort, an air passageway from saidblower to said retort, a

damper for controlling the entrance of air to ."J

said blower; the combination with .said stoker, or afioat chamber, afloat in said float chamber,-

means connecting said float to said 'damper', an

hermetically sealed chamber, a conduit from said hermetically sealedchamber to said float chamber, liquid in saidchambers, a pressure pipein said hermetically sealed chamber, and having one of its ends locatedabove the level of other. end connected into said air passageway,.

of said motors and operatively connected to said and actuated thereby tocontrol said coal feed motor and said air blower motor andautomatioallythereby the amount of coal and air fed to's'aid-retort.

'- 7. In-ia coal stoker of the character wherein the' stoker is providedwith coal feed means, a

afor drivingsaid coal feed means, an air blcwer asecond-motor foroperatingsaid air blower, a hopper for coal, a retort, a coal passagewayfrom said hopper to said retort, an air passageway from said blower tosaid retort, a damper for controlling the entrance of air to saidblower; the combination with said stoker, of a float chamber, a float insaid float chamber, means connecting said float to said damper, anhermetically sealed chamber, a conduit from said hermetically sealedchamber to said float chamber, liquid in said chambers, a pressure pipelocated in said hermetically sealed chamber, and having one of its endslocated above the level of the liquidin said last-named chamber, andhaving its other end connected into said air passageway, a rotatabledisk operatively connected to said damper, a plurality of mercury tubeswitches mounted on said disk, said switches being electricallyconnected to said coal feeding motor and said air blower motor toautomatically thereby control the amount ofcoal and air feed to saidretort.

8. In a coal stoker of the character wherein the stoker is provided withcoal feed means, a motor for driving said coal feed means, an airblower, a second motor for operating said air blower, a hopper for coal,a retort, a coal passageway from said hopper to said retort, an airpassageway from said blower to said retort, a damper for controlling theentrance of air to said blower; the combination with said stoker, of afloat chamber, a float in said float chamber, means connecting saidfloat to said damper, an hermetically sealed chamber, a conduit fromsaid hermetically sealed chamber to said float chamber, liquid in saidchambers, a pressure pipe located in said hermetically sealed chamberhaving one of its ends located above the level of the liquid in saidlast-named chamber, and having its other end connected into said airpassageway, a rotatable disk operatively connected to said damper, a

plurality of mercury tube switches mounted on said disk, said switchesbeing electrically connected to said coal feeding motor and said airblower motor to automatically thereby control the amount of coal and airfed to said retort, said blower motor having a plurality of speeds andone of said mercury tubes having two sets of contacts connected to saidblower motor, one set of contacts being opened and the other set beingbination with such means of means for auto-,

matically operating said damper, and including pressure operated meansactuated by differences of pressure within said air passageway, tothereby actuate said damper, and a plurality of electrical switch meansoperated by said damper and electrically connected to each of said motormeans to thereby control the operation of the same.

10. In a coal stoker of the character wherein the stoker is providedwith motor means for feeding coal and separate motor means for feedingair into a combustion chamber, and including a blower driven by saidmotor means, a blower damper and air and coal passageways; thecombination with such means, of means for automatically operating saiddamper, and including pressure operated means actuated by difierences.

of pressure within said air passageway, to thereby actuate said damper,and a plurality of electrical switch means operated by said damper, andelectrically connected to each of said motor means to thereby controlthe operation of the same, one of said switch means including a rheostatswitch connected to said fan blower motor.

11. In a coal stoker of the character wherein the stoker is providedwith motor means for feeding coal and air into a combustion chamber andincluding a blower driven by said motor means, a damper on said blower,and air and coal passageways to said combustion chamber; the combinationwith such means, of pressure means for operating said damper, saidpressure means being actuated by diiferences of pressure within said airpassageway, said motor. means comprising a two-speed motor for feedingair, and a single speed motor for feeding coal, and means actuated bysaid pressure means for controlling the operation of both motors.

12. In a coal stoker of the character wherein the stoker is providedwith motor means for feeding coal and air into a combustion chamber, andincluding a blower driven by said motor means, a damper on said blower,and air and coal passageways to said combustion chamber; the combinationwith such means, of pressure means for operating said damper, saidpressure means being actuated by diiferences of pressure within said airpassageway, said motor means including a motor for feeding air, and aseparate motor for feeding coal, and mercury tube switch means actuatedby said pressure means for controlling said motors.

13. In a coal stoker of the character wherein the stoker is providedwith motor means for feed ing coal and air into a combustion chamber,and including a blower driven by said motor means, a damper on saidblower having supporting means therefore, and air and coal passagewaysto said combustion chamber; the combination with such structure, ofpressure means for operating said damper, said pressure means beingactuated by diiferences of pressure within said air passageway, andswitch means mounted on said damper supporting means for controllingsaid motor means, said switch means having means for controlling thespeed of said blower at high and low speeds, and said switch meansincluding means for stopping the feeding or coal when the .blower isoperating at high speed.

14. In a coal stoker of the character wherein the stoker is providedwith motor means for feeding coal and air into a. combustion chamber,and including a blower driven by said motor means, a damper on saidblower, and air andcoal passageways to said combustion chamber; thecombination with such means, of pressure means for operating saiddamper, said pressure means being actuated by difierences of pressurewithin said air passageway, a rotatable support, rotatable by saiddamper, and mercury tube switch means mounted on said support, saidswitch means havincluding a blower driven by said motor means,

air and coal passageways, and damper means for said blower; thecombination with such means, of pressure means for operating said damperthe speed of said blower at high and low speeds,

and said switch means including means for stopping the feeding of coalwhen the blower is operating at high speed.

FREDERICK A. HELLMANN. HARRY R. STATHAM.

